Externally anchored tether for altering airbag deployment

ABSTRACT

An example airbag arrangement includes an example airbag moveable between an expansion-constrained position and an expanded position. The airbag includes a contact face. A tether has a first end connected to the contact face and a second end anchoring the tether. The tether holds the contact face of the airbag in a substantially vertical position.

BACKGROUND OF THE INVENTION

This invention relates to constraining an airbag during deployment using an externally anchored tether.

Known airbag systems protect vehicle occupants by absorbing forces generated during collisions, for example. Many airbag systems are used in conjunction with other vehicle safety systems, such as seat belts. Safety systems protect occupants located in various positions within the vehicle.

In particular, airbag designs within some safety systems protect both “in-position” occupants and “out-of-position” occupants. Typically, during a collision, an “in-position” occupant directly strikes a generally vertical contact face portion of the airbag, whereas an “out-of-position” occupant does not directly strike the contact face. Balancing protection of “in-position” occupants with protection of “out-of-position” occupants is often challenging. Through the contact face, the airbag absorbs forces from the occupant that are generated during the collision. Directly striking the contact face facilitates force absorption.

Generally, it is desirable to provide a substantially planar vertically-oriented contact face when the airbag is fully expanded, as this orientation enhances absorption of forces from the “in-position” occupant. Although providing a generally planar vertical contact face is desirable when the airbag is fully deployed, airbags may have other orientations during deployment. Some of the other orientations can undesirably strike an occupant as the airbag deploys. Such occupants may include a child standing on the floor of a vehicle in front of a passenger airbag or a child moving toward the front of the vehicle as the passenger airbag deploys.

SUMMARY OF THE INVENTION

An example airbag arrangement includes an airbag moveable between an expansion-constrained position and an expanded position. The airbag includes a contact face. A tether has a first end connected to the contact face and a second end anchoring the tether. The tether holds the contact face of the airbag in a substantially vertical position.

The example airbag arrangement may include an expandable airbag having a contact face. A tether has a first end that connects to the contact face and a second end that anchors the tether. The tether constrains expansion of the airbag to move the contact face to a substantially vertical position during initial deployment.

An example method of constraining an airbag includes anchoring a contact face of an airbag and expanding the airbag. The method orients the contact face vertically during expansion.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of an embodiment of the invention. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 shows an “out-of-position” occupant and a prior art airbag assembly moving toward an expanded position;

FIG. 2 shows a front view of the FIG. 1 prior art airbag assembly;

FIG. 3 shows an “out-of-position” occupant and an example airbag assembly in an expansion-constrained position;

FIG. 4 shows a front view of the FIG. 3 airbag assembly;

FIG. 5 shows a side view of an “in-position” occupant and the example airbag assembly in an expanded position;

FIG. 6 shows a front view of a FIG. 5 airbag assembly;

FIG. 7 shows a close-up side view of the example tether of FIG. 3;

FIG. 7A shows a close-up side view of another example tether of FIG. 3;

FIG. 8 shows a close-up side view of the example tether of FIG. 5; and

FIG. 8A shows a close-up side view of another example tether of FIG. 5.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT

Referring to FIGS. 1 and 2, in a prior art airbag assembly 100, an airbag 114 has a tilted contact area 118 during deployment. The tilted contact area 118 contacts an “out-of-position” occupant, such as a child 122 standing on a vehicle floor 126 in front of a passenger seat 130 during deployment of the airbag 114. As the contact area 118 is generally directed upward during the early stages of deployment, the contact area 118 may contact just the head and neck area of the child 122 and, in some examples, directly strikes the chin of the child.

An example airbag assembly 10 in an expansion-constrained position includes a tether 18 anchoring a portion of an airbag 14 during airbag deployment, as shown in FIGS. 3 and 4. The tether 18 connects at one end to a contact face area 22 of the airbag 14 and anchors at the other end to the vehicle 26, for example.

Tethering the airbag 14 affects the deployment characteristics of airbag 14. In this example, the tether 18 tends to direct a lower portion 30 of the airbag 14 toward a vehicle floor 34, and holds the lower portion 30 of the airbag 14 closer to the front of the vehicle 26 during the initial stages of airbag 14 deployment.

The tether 18 causes the contact face 22 of the airbag 14 to maintain a generally vertical profile during the initial deployment stage, and a profile generally flat and perpendicular to the vehicle floor 34. The initial deployment stage generally corresponds to the first 20 milliseconds of deployment. The shape of the airbag 14 is important during this stage. Such a profile tends to strike an “out-of position” occupant, such as a child 38, in the head, neck, chest, and shoulders rather than just the head or chin and neck. Accordingly, forces generated during airbag deployment are distributed across a greater area of the “out-of position” occupant than in the prior art. Distributing the forces in this manner provides a softer deployment for the “out-of-position” occupant.

Referring now to FIGS. 5 and 6, the tether 18 has a longer intact position when the airbag 14 is in the fully expanded position. The longer intact position of the tether 18 permits the airbag 14 to fully expand to a position suitable for protecting an “in-position” occupant 42. In the fully expanded airbag 14, the contact face 22 maintains a generally vertical orientation. The shorter intact position vertically aligns the contact face 22 during deployment by constraining expansion with the shorter intact tether 18. The longer intact position of the tether 18 permits the generally vertical contact face 22 when the airbag 14 is fully expanded.

The tether 18 incorporates features that permit tether 18 movements between the shorter intact position and the longer intact position. As shown in FIGS. 7 and 8, stitches 46 hold the position of folds in the tether 18 during initial deployment of the airbag 14. Exerting force on the tether 18 tears the stitches 46 permitting the tether 18 to unfold an increasing the tether 18 length. Other stitches 48 maintain the position of the tether 18 relative the airbag 14.

Tearing the stitches 46 requires more force than expanding areas of the airbag 14 away from the lower portion 30. But once those areas expand, the expansive forces exerted by the airbag 14 on the tether 18 tear the stitches 46. The tether 18 remains intact even if the stitches 46 tear.

Although described as increasing the length of the tether 18 by tearing the stitches 46, those skilled in the art and having the benefit of this disclosure would understand that other features can be used to hold the tether 18 at a shorter length, and then increase the tether 18 length under force. For example, the tether 18 may include a polymer portion that deforms under load and increases the effective length of the tether 18. In still other examples, it may be desirable to break a portion of the tether 18 such as shown in FIGS. 7A and 8A as the airbag 14 moves from the expansion constrained position to the expanded position. In such examples, the tether 18 includes an aperture 20, which tends to cause the tether 18 to break in an area near the aperture.

In addition to the tether 18, other features may facilitate control of the airbag 14 expansion. For example, an upper portion 31 of the airbag 14 may include vents 50 as shown in FIG. 6. The vents 50 slow the expansion of the upper portion 31 as some of the air moving into the upper portion 31 of the airbag 14 escapes though the vents 50. Slowing the expansion of the upper portion 31 helps vertically orient the airbag 14 during the expansion-constrained portion of airbag 14 deployment.

Changing the size of the vents 50 alters the expansion characteristics of the airbag 14 and the associated expansion speed of the lower portion 30. Thus, the vents 50 can be used to tune the expansion of the airbag 14.

Referring again to FIG. 6, the location of the vents 50 may further affect the expansion characteristics. In this example, the airbag 14 expands from a 50/50 folded position. Approximately half of the folded area includes the lower portion 30 of the airbag 14, and the other half of the folded area includes the upper portion 31 of the airbag 14. The vents 50 are located within the upper portion 31 so that in the 50/50 folded position, the vents 50 are exposed on the top of the folded airbag 14.

Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. 

We claim:
 1. An airbag arrangement, comprising an airbag moveable between an expansion-constrained position and an expanded position; a contact face of said airbag; and a tether having a first tether end connected adjacent said contact face and a second tether end anchoring said tether, wherein said tether limits expansion of a lower portion of said airbag to hold said contact face in a substantially vertical position during movement of the airbag to said expanded position.
 2. The airbag arrangement of claim 1, wherein a plane established by said contact face of said airbag in said expanded position is aligned with a plane established by said contact face of said airbag in said expansion-constrained position.
 3. The airbag arrangement of claim 1, wherein said contact face of said airbag in said expansion-constrained position is configured to contact a chest area of an occupant and a head area of the occupant at the same time.
 4. The airbag arrangement of claim 1, wherein a length of said tether increases as said airbag moves from said expansion-constrained position to said expanded position.
 5. The airbag arrangement of claim 1, wherein said tether is moveable by said airbag between a shorter intact position and a longer intact position, wherein said tether in said shorter intact position holds said airbag in said expansion-constrained position.
 6. The airbag arrangement of claim 1, wherein said second tether end connects adjacent a base of said airbag.
 7. The airbag arrangement of claim 1, including one or more vents in an upper portion of said airbag.
 8. The airbag arrangement of claim 1, wherein the tether holds the contact face in a substantially vertical position during initial deployment.
 9. The airbag arrangement of claim 1 wherein said tether contacts a lower portion of said airbag to hold said contact face in said substantially vertical position.
 10. The airbag arrangement of claim 1 wherein said airbag is a passenger side airbag.
 11. An airbag arrangement, comprising an expandable airbag; a contact face of said airbag; and a tether having a first tether end connected to said contact face and a second tether end for anchoring said tether, wherein said tether constrains expansion of said airbag to move said contact face to a substantially vertical position during an initial deployment.
 12. The airbag arrangement of claim 11, wherein said tether has a shorter intact position for constraining expansion of said airbag and a longer intact position for permitting expansion of said airbag beyond said substantially vertical position.
 13. The airbag arrangement of claim 11, including one or more vents in an upper portion of said airbag. 